1. Field of the Invention
The present invention relates generally to cellular and local area networks (LANs)/wireless LANs (WLANs), and more specifically, to methods and apparatus for determining the location of subscribers within integrated cellular and LAN/WLAN networks.
2. Description of Related Art
Referring to FIG. 1, there is illustrated an example functional architecture of a generic cellular network 100 of the prior art. This network comprises a core network 102 interconnected to a plurality of radio access networks (RAN) 104, which in turn interface to a plurality of mobile stations 106 (generically referred to as user equipment) through a wireless access interfaces 108. Note that the radio access networks may be GSM/GPRS/UMTS type access networks, for example. As such, cellular network 100 may be a network as defined by the 3rd Generation Partnership Project (3GPP). As is known, a given cellular service provider's network will typically comprise a plurality of networks resembling network 100, as additionally depicted by cellular network 100a. As is also known, there are multiple service providers today, each of which will have networks resembling networks 100/100a, for example. In general, each cellular network 100, both within and across service providers, is interconnected (as illustrated by lines 110) in an appropriate fashion, including signaling and bearer channels, to allow cross communication between multiple cellular networks and between cellular networks and traditional networks, such as the public switched telephone network (PSTN) 112.
As indicated, mobile stations 106 interface/access cellular network 100 through one of a plurality of radio access networks 104, each radio access network managing the wireless access interface to the mobile stations for a given cellular region. As further illustrated in FIG. 1, each core network 102 comprises a mobile switching center (MSC) 114 and a serving general packet radio system (GPRS) support node (SGSN) 116, each of which interfaces the core network to one or more radio access networks 104. Through the MSC and SGSN, a cellular network 100 provides both circuit switched services (e.g., voice calls) and packet switched services (e.g., web browsing) to mobile stations. More specifically, MSC 114 is responsible for performing switching functions related to circuit-based connections between mobile stations. MSC 114 also provides connection to external networks, such as PSTN 112, and in this way, performs switching functions related to circuit-based connections between mobile stations and end-users on the PSTN. Similarly, SGSN 116 is responsible for performing switching functions related to packet-based connections between mobile stations and other network elements. In addition, through gateway GPRS support node (GGSN) 117, SGSN 116 provides mobile stations with connections to external packet networks 118, such as private networks and/or the Internet.
As further illustrated in FIG. 1, core network 102 also comprises a home location register (HLR)/home subscriber server (HSS) 120 (hereinafter collectively referred to as the HLR) and a visitor location register (VLR) 122, which together, as is known, provide the routing and roaming capabilities within cellular networks. Specifically, each mobile station 106 is associated with or registered with a given cellular network 100, which is referred to as the mobile station's home network. A mobile station can also roam outside its home network to other cellular networks 100 both within the mobile station's service provider network and to the networks of other providers. Cellular networks beyond a mobile station's home network are referred to as visited networks. Significantly, all administrative information related to a mobile station, including the mobile station's current location (i.e., to which core access network 100 is the mobile station currently connected), are stored in the HLR of the mobile station's home network.
More specifically, when roaming to a visited network for example, a mobile station registers with the MSC 114 and/or SGSN 116 within that visited network, causing selected information related to the mobile station to be stored within VLR 122 of the visited network. More importantly, as is known in the art, as part of this registration process the HLR of the mobile station's home network is essentially updated with a location/address that can be correlated to the visited network's MSC/SGSN (i.e., the HLR is essentially updated with the address of the MSC or SGSN to which the mobile station registers). As such, the HLR maintains the current location of the mobile station, enabling the mobile station to be located.
As an example, when a call is placed to a mobile station, the mobile station's HLR is determined, using for example, the mobile station's phone number. The HLR is then queried to determine whether the mobile station is within its home network or a visited network. If within a visited network, the HLR provides routing information corresponding to the MSC/SGSN of the visited network, allowing the call to be properly routed to the MSC/SGSN of the visited network and onto the radio access network in which the mobile station is currently located (as is known, this location mechanism provided by the HLR typically occurs through interactions between the HLR and the VLR of the visited network).
Within the context of cellular networks, cellular service providers have realized that there is a need and benefit for location-based services (LBS), or in other words, for being able to determine the physical/geographic location of mobile stations (i.e., not only determining which core access network the mobile station is currently in as described above, but for determining the actual physical location of the mobile station, such as longitude and latitude coordinates). For example, when a mobile subscriber dials 911, it is necessary to determine the physical location of that subscriber/mobile station. From a commercialization standpoint, location-based services also provide additional revenue to cellular service providers. For example, through location-based services, cellular service providers can provide a service to mobile subscribers that allows subscribers to request their own locations and thereby directions to desired locations. Similarly, through location-based services, cellular service providers can provide a service to external customers, such as advertisers, that allows advertisers to request the location of mobile stations and to then send advertisements related to stores geographically near those mobile stations. One skilled in the art will readily realize that there are numerous other uses and benefits to being able to determine the physical location of mobile stations.
In response to this need for location-based services, standards bodies, such as the 3GPP, have defined standards for providing location-based services within cellular networks (see, e.g., “3GPP TS 23.171: Functional stage 2 description of location services in UMTS,” and related documents). Assuming all cellular service providers implement such standards, there now exists the ability to ubiquitously determine the location of a mobile station, no matter which cellular network 100 the mobile station is located. For example, each cellular service provider can provide location-based services to an LBS client 124 (see FIG. 1). This LBS client may be internal to a cellular service provider, such as a 911 operator, or may be an external customer of the cellular service provider, such as a mobile subscriber. This LBS client can make a request to any given service provider for the location of a mobile station and through location-based services, the physical location (e.g., longitude and latitude coordinates) of that mobile station can be provided regardless of whether that mobile station is within its home network or a visited network of its own provider or another provider.
For example, according to 3GPP standards, location-based services are provided through the incorporation of a gateway mobile location center (GMLC) 126 within core network 100 and through added functionality to the MSC, SGSN, radio access networks, and possibly the mobile stations. In general, an LBS client 124 accesses a GMLC 126 of a core network and requests the location of a particular mobile station 106, specifying an identity for the mobile station (e.g., the mobile station's phone number). Based on this request, GMLC 126 accesses the indicated mobile station's HLR and determines the MSC/SGSN to which the mobile station is currently registered. This operation is similar to determining the location of a mobile station for call routing purposes. Once knowing the MCS/SGSN, the GMLC forwards the request to the determined MSC/SGSN, for example, which in turn forwards the request to the radio access network to which the mobile station is currently associated. The radio access network then proceeds to determine the physical location of the mobile station. For example, the radio access network may request that the mobile station tune to GPS satellites to obtain the mobile station's current coordinates. Once having the mobile station's location, the radio access network then returns the location to the GMLC through the MSC/SGSN. The GMLC then returns the location to LBS client 124.
In addition to cellular networks, wireless local area networks (WLANs) are also experiencing large growth. As compared to the packet services provided by cellular networks, WLAN networks typically provide higher speed data access. In addition, rather than providing the broad coverage typically found in cellular networks, WLAN networks are typically deployed, at present, in a localized fashion (i.e., hotspots), such as airports, hotels, shopping malls, coffee houses, homes, etc. Referring now to FIG. 2, there is illustrated a functional architecture of an example WLAN network 200 of the prior art. As illustrated, example WLAN network 200 is an IP-based network that comprises a plurality of network elements including an IP backbone network 202 that interconnects a plurality of access points (APs) 204, which in turn interface to a plurality of WLAN clients 206 (generically referred to as user equipment) through wireless access interfaces 208, such as Bluetooth or IEEE 802.11a/b/g. As shown, WLAN networks typically interconnect to the Internet 210.
Similar to cellular networks, location-based services also exist for WLAN networks. Such services determine and report the geographic/physical location of a WLAN client. However, existing systems that provide location-based services for WLAN networks are typically proprietary and specific to a given WLAN network, prohibiting the easy integration across WLAN networks. For example, although WLAN networks are interconnected through the Internet, for example, because of the proprietary nature of the different systems, it is not possible to access a single interface and locate a WLAN client regardless of which WLAN network the client is currently associated with.
As is also known, WLAN networks are being integrated with cellular networks. For example, the 3GPP has defined standards for the integration of GSM/GPRS/UMTS based cellular networks with WLAN networks (see, e.g., “3GPP TS 23.234: WLAN Subsystem; System Description,” and related documents). Referring to FIG. 3, there is illustrated an example functional architecture of an integrated cellular and WLAN network 300 of the prior art. Again, a given service provider's network will typically comprise a plurality of networks resembling network 300. As seen, core network 302 of the cellular network continues to interconnect to a plurality of radio access networks 104/mobile stations 106 through MSC 314 and SGSN 316, as described above. However, core network 302 now also interconnects to a plurality of WLAN networks 202 and WLAN clients 306. As illustrated in this example network, the interconnection between the WLAN networks 202 and core network 302 occurs through MSC 314 and SGSN 316 of the core network and through the addition of gateway 330 to WLAN networks 202. In general, this integrated network allows WLAN clients 306 to utilize the services of the cellular network, including circuit switched services through the MSC and packet based services through the SGSN.
In this integrated network, a WLAN client 306 is administratively handled similar to a mobile station 106. Specifically, each WLAN client can roam between different networks 300, similar to mobile stations. As such, each WLAN client is assigned a home network and has an entry within its home network's HLR 320, similar to a mobile station. In addition, each WLAN client is tracked by its HLR similar to how mobile stations are tracked and as such, each HLR knows the current location of its WLAN clients (i.e., to which core access network 300 is the WLAN client currently connected). Specifically, each time a WLAN client 306 is powered on in a network 300 or moves between networks 300, WLAN client 306 will register with MSC 314 and/or SGSN 316 that is connected to the WLAN network in which the WLAN client is currently located. The result of this registration resembles that of a mobile station, causing the HLR of the WLAN client's home network to be updated with a location/address that can be correlated to the MSC or SGSN to which the WLAN client is currently registered. Again, this allows the WLAN client's HLR to be queried to determine in which WLAN network the WLAN client is currently located.
Significantly, ubiquitous location-based services do not exist in these integrated cellular and WLAN networks. In other words, an LBS client 124 requesting that GMLC 126 determine the location of a particular mobile subscriber will only be able to find the location of mobile stations 106 connected to radio access networks 104 and will not be able to determine the location of WLAN clients 306 connected to WLAN networks 202. In order to determine the physical location of a WLAN client, one of the WLAN network specific protocols must be used.
This lack of a ubiquitous location-based service presents several problems. Significantly, in this integrated architecture, WLAN clients will be able to make voice calls, for example. However, it will be difficult to determine whether these voice calls originate from the traditional cellular network or from the WLAN networks. This presents a problem when emergency calls are made from WLAN networks because 911 operators now may need to make several requests, to both the cellular network and to the individual WLAN networks, to find a caller. In addition, it is also difficult for a service provider of such an integrated network to provide commercial-based services because there is no one single procedure that can be used to locate a subscriber.